The Japanese counting system has been taken over from the Chinese. Where our counting system counts up to 1,000, the Japanese and Chinese system counts up to 10,000.

Another difference is the way numbers are constructed. The basic rule is that the location of the digit is indicated like in "two thousand five hundred". When counting from 1 to 10 "shi" is used for 4 and "shichi" for 7, but when using numbers the preference is given to the readings "yon" for 4 and "nana" for 7.

Some combinations get contractions.

一(ichi) is only placed before 万 (man), 億 (oku), 兆 (chou) and 京 (kei). 十 (juu), 百 (hyaku) and 千 (sen) are never preceded by 一 (ichi)

Unlucky numbers
4 and 9 are considered unlucky numbers in Japanese because of sound association. "Shi" (4) is associated with death (死, shi) and "ku" (9) is associated with suffering (苦, ku).

Telephone Numbers
Telephone numbers are often read with the following pronunciations:

The fictional phone number 0312-54-9678 would then be read as:
"maru san hito ni no go yon no kyuu roku nana hachi".

Counting Time
When counting time elements several irregularities occur.

Age
For counting one's age you use the classifier 才 or 歳 (sai). Here too several contractions occur, but especially "20 years old" has an irregular reading.

Hours
Hours are counted with two different classifiers, depending on whether you are counting the duration of time, 時間 (jikan), or reading time, 時 (ji). Pay particular attention to numbers ending on 4, 7, and 9.

Days
Days can be counted as days of the month, or the number of days. In particular 1 - 10, 14, 20, and 24 are irregular. Every number ending on 4 has the same irregularity as 14 and 24.

Months
Months are counted regular, but again the distinction is made between a number of months and the twelve months of the year. Note the difference between the reading of 月 (getsu / gatsu).

Years
Four digit years are always pronounced in full, and not as in English "eighteen sixty eight". When written in kanji you may encounter years without the identifiers. When written in this way, the zero is written as a circle (maru).

NOTE: 年 (nen) can be used both for counting years and to describe a timespan in years. 年間 (nenkan) can only be used to describe a timespan.
In Japan both the Gregorian calendar and the Japanese calendar are used. In the Japanese calendar, years are started from count one at the rule of a new emperor. For more information click here.

Classifiers
When counting anything you will need classifiers. Classifiers identify the type of object you are counting. To give you an example, when you want to say "three cars" you can't simply say 三車(san kuruma), you will need the classifier for machinery 台 (dai): 三台の車 (san dai no kuruma) or 車三台 (kuruma san dai).

NOTE: You can place the number plus classifier before the counted object by using the particle の (no), if you place the number after the object being counted you don't use の (no).

Though the Japanese prefer to use the correct classifier, there are so many that even the Japanese don't know all of them. In these cases the Japanese reading for the numbers 1 - 10 is used, for higher numbers the normal Chinese reading you've seen above is used.

Classifier overview
Here you will find the most common classifiers and the type of object they are used for. Below these you will find the irregular combinations where they exist.